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	Hubble's law - Wikipedia, the free encyclopedia
		Hubble's law is the statement in physical cosmology that the redshift in light coming from distant galaxies is proportional to their distance.
		Though there was considerable scatter (now known to be due to peculiar velocities), Hubble was able to plot a trend line from the 46 galaxies he studied and obtained a value for the Hubble constant of approximately 400 km/s/Mpc, which is much higher than the currently accepted value due to errors in his distance calibrations.
		The value of the Hubble constant was the topic of a long and rather bitter controversy between Gérard de Vaucouleurs who claimed the value was 100 and Allan Sandage who claimed the value was 50.
	en.wikipedia.org /wiki/Hubble_constant (1386 words)

	Hubble Constant
		The value of the Hubble Constant is important for both observations of the objects in the Universe, as it allows us to convert their recession velocities into true distances, and for estimating the age of the Universe.
		Below is shown Hubble's original figure from the 1929 paper - where he plotted the radial velocities in km/sec of the galaxies against his estimates of their distances (in parsecs) derived from the apparent magnitudes of what he thought were the bright supergiant stars.
		Hubble Space Telescope were to use it to measure the sizes of distant galaxies and to detect the variations in the luminosity of variable stars in distant galaxies.
	www.phys.unsw.edu.au /astro/wwwlabs/hdfSize/hdfSize_intro.html (1451 words)

	Hubble Constant (Site not responding. Last check: 2007-11-05)
		Hubble's original value for H was 150 km (93 miles) per second per 1,000,000 light-years.
		The reciprocal of Hubble's constant lies between 10 billion and 20 billion years, and this cosmic time scale serves as an approximate measure of the age of the universe.
		The Hubble constant also has the property of being related to the age of the Universe, which undoubtedly explains some of the interest in its value.
	homepage.ntlworld.com /brian.kilby/astro/1999/oct/hubble-constant.html (706 words)

	Hubble Constant Refined and Positive Cosmological Constant Postulated - Does God Exist? - JulAug00
		This is now called Hubble's constant, which is just the measure of the expansion rate (and not to be confused with the cosmological constant of Einstein's equations).
		The inverse of Hubble's constant is proportional to the size of the universe.
		The latest round of measurements in 1999 indicate a currently accelerating expansion rate--a positive cosmological constant- (with a Hubble constant of 60-70 km per second per mparsec), whereas in the past history of the universe the expansion was slowing--or had a zero or even negative cosmological constant.
	www.doesgodexist.org /JulAug00/HubbleConstantRefinedAndPositiveCosmologicalConstantPostulated.html (2694 words)

	HubbleSite - Release Text about "Hubble Completes Eight-Year Effort to Measure Expanding Universe" (Site not responding. Last check: 2007-11-05)
		Measuring the Hubble constant was one of the three major goals for NASA's Hubble Space Telescope before it was launched in 1990.
		For the past 70 years astronomers have sought a precise measurement of the Hubble constant, ever since astronomer Edwin Hubble realized that galaxies were rushing away from each other at a rate proportional to their distance, i.e.
		Combining the Hubble constant measurement with estimates for the density of the universe, the team determined that the universe is approximately 12 billion years old - similar to the oldest stars.
	www.hubblesite.org /newscenter/newsdesk/archive/releases/1999/19/text (730 words)

	Hubble law and the expanding universe
		Hubble's law is a statement of a direct correlation between the distance to a galaxy and its recessional velocity as determined by the red shift.
		The proportionality between recession velocity and distance in the Hubble Law is called the Hubble constant, but the value of this proportionality is a source of disagreement.
		The Hubble Law states that the distance to a given galaxy is proportional to the recessional velocity as measured by the Doppler red shift.
	hyperphysics.phy-astr.gsu.edu /hbase/astro/hubble.html (578 words)

	Sacramento Peak: Hubble Constant (Site not responding. Last check: 2007-11-05)
		Edwin Hubble's observations look just like those of the creatures in Balloon World, except that the creatures of Balloon World and their measurements are two-dimensional, whereas Hubble and we live in a three-dimensional world.
		Hubble's constant H is the ratio between the distance to a far-away object and its speed away from us (after taking out the speed of the object relative to its surroundings).
		The unit that is commonly used for Hubble's constant, kilometers per second per megaparsec, is actually a unit for frequency, equal to 3.24e-20 Hz.
	www.sunspot.noao.edu /sunspot/pr/tree/hubble-constant.html (1084 words)

	Hubble constant starts to settle down (May 1999) - News - PhysicsWeb
		The Hubble team, led by Wendy Freedman of the Observatories of the Carnegie Institution of Washington, has spent the last eight years using the telescope to make more accurate measurements of the Hubble constant – the rate at which the universes expands.
		To calculate the age of the universe from the Hubble constant it is necessary to know both the density of matter in the universe and the value of the cosmological constant.
		The Hubble team assumed that the density was critical - that is, high enough to eventually stop the expansion of the universe, but not enough to cause the universe to collapse back in on itself.
	physicsweb.org /article/news/3/5/12/1 (547 words)

	Scientists Find the True Hubble Constant!
		The Hubble Constant is the speed which the Universe is expanding at.
		Now that the Hubble team has found Hubble's Constant to be 70 kilometers per second per megaparsec, they have determined the age of the Universe to be 12 billion years old.
		Finding the Hubble Constant was one of three original goals set by astronomers when the telescope was first launched in 1990.
	www.windows.ucar.edu /tour/link=/headline_universe/hubble_constant.html (283 words)

	Expanding Universe
		Hubble, who had been the first to establish that the universe included many other galaxies outside of our own, noticed something else: the galaxies were receding from us at a velocity proportional to their distance.
		Determining the Hubble Constant is something of a Holy Grail for cosmologists, because it holds the key to the age of the universe.
		Because the Hubble Constant is a measure of how much space is expanding in units of distance per second, it's possible to estimate how long it would take, rolling the movie backwards, for the most distant galaxies to collide with each other and finally collapse in the Big Bang.
	archive.ncsa.uiuc.edu /Cyberia/Cosmos/ExpandUni.html (1154 words)

	Hubble's Law
		Hubble's Law states that the farther away a galaxy is from its observer, the faster it appears to be moving away from the observer.
		Hubble's constant provides the basis for this law (its symbol is H-subscript-O, but as it is difficult to type a subscript, I will use Ho to represent Hubble's constant).
		Hubble's Law, important as it was for proving that the universe is expanding, also proved that the universe is expanding isotropically, that is, equally in all directions.
	www.upei.ca /~physics/p221/pro99/hubble/hubble.htm (1697 words)

	A Science Odyssey: People and Discoveries: Edwin Hubble (Site not responding. Last check: 2007-11-05)
		Edwin Powell Hubble is renowned for determining that there are other galaxies in the Universe beyond the Milky Way, and for observing that the universe is expanding at a constant rate.
		Hubble was a tall, elegant, athletic, man who at age 30 had an undergraduate degree in astronomy and mathematics, a legal degree as a Rhodes scholar, followed by a PhD in astronomy.
		Hubble calculated it to be about 2 billion years ago, but more recent estimates have revised that to 20 billion years ago.
	www.pbs.org /wgbh/aso/databank/entries/bahubb.html (295 words)

	APOD: May 14, 1996 - Hubble's Constant And The Expanding Universe (II) (Site not responding. Last check: 2007-11-05)
		Two groups of astronomers trying to measure this fundamental constant using the Hubble Space Telescope (HST) are continuing to report conflicting results.
		Their results favor a relatively small Hubble constant (slow expansion rate) of about 55 kilometers per second per megaparsec which means that galaxies one megaparsec (3 million lightyears) distant appear to recede from us at a speed of 55 kilometers per second.
		A substantially faster expansion rate (larger Hubble constant) is being reported by astronomer Wendy Freedman and collaborators, also based on HST data.
	antwrp.gsfc.nasa.gov /apod/ap960514.html (268 words)

	Hubble constant Comparison Table
		The Hubble constant is equal to the recessional speed of a distant galaxy, divided by its distance from us.
		Assuming a homogeneous and isotropic universe, the recessional speed of a distant galaxy is proportional to its distance; thus the Hubble constant as determined by any receding galaxy should be the same, yielding a universal rate of expansion of the universe.
		According to estimates, the current value of the Hubble constant is approximately 100 km/s/Mpc, meaning that the distance between any two distant galaxies will double in about 10 billion years at the current rate of expansion.
	www.csi.uottawa.ca:4321 /astronomy/Hubbleconstant_table.html (149 words)

	HST findings shed new light on the fate of the Cosmos
		Hubble had the insight to realize that not only were these objects apparently speeding away, but the farther away they were, the faster they appeared to be moving.
		The Hubble Constant is usually expressed in units of "kilometers per second, per Megaparsec." One parsec is a unit of distance equal to about 3.2 light years, and a Megaparsec is a million times this, or about 3.2 million light years.
		By measuring the Hubble Constant and multiplying by the age of the Universe, we are restricted to live on one of these curves.
	science.nasa.gov /newhome/headlines/ast25may99_2.htm (2311 words)

	Hubble time concept from the Astronomy knowledge base
		For a flat universe with no cosmological constant, the age of the universe is two-thirds of the Hubble time.
		For a Hubble constant of 50, one can calculate that the Hubble time is 19.6 billion years; for a Hubble constant of 80, the Hubble time is 12.2 billion years.
		In particular, if the mass density of the universe (designated Ω) is 0.1, the universe's age is 90 percent of the Hubble time; if Ω is 1.0, the universe's age is 67 percent of the Hubble time.
	www.site.uottawa.ca:4321 /astronomy/Hubbletime.html (173 words)

	The Hubble Law (Site not responding. Last check: 2007-11-05)
		The Hubble constant H is of particular significance; it is defined as a measure of how fast the universe is expanding.
		Hubble initially derived an inaccurate distance of 930,000 light years for Andromeda, today known to be about 2.2 million light years away.
		The constant is a measure of how fast the universe is expanding, and this expansion would have been greater when the universe was young.
	www.answersingenesis.org /home/area/magazines/tj/docs/tj_v9n1_hubble.asp (3433 words)

	The Hubble Constant (Site not responding. Last check: 2007-11-05)
		The Hubble Constant (Ho) is one of the most important numbers in cosmology because it is needed to estimate the size and age of the Universe.
		In 1929, American astronomer Edwin Hubble announced his discovery that galaxies, from all directions, appeared to be moving away from us.
		The units of the Hubble Constant are "kilometers per second per megaparsec." In other words, for each megaparsec of distance, the velocity of a distant object appears to increase by some value.
	csep10.phys.utk.edu /guidry/violence/hubble_constant.html (478 words)

	HubbleSite - Astrofiles about "Hubble Space Telescope Measures Precise Distance to the Most Remote Galaxy Yet" (Site not responding. Last check: 2007-11-05)
		Reliable distance measurements are a crucial factor in determining a precise value for the universe's expansion rate (called the Hubble Constant) which is needed to estimate the size and age of the universe.
		The Hubble Constant can be stated as a simple mathematical expression, Ho = v/d, where v is the galaxy's radial outward velocity (in other words, motion along our line-of-sight), d is the galaxy's distance from earth, and Ho is the current value of the Hubble Constant.
		The value of the Hubble Constant initially obtained by Edwin Hubble was around 500 km/s/Mpc, and has since been radically revised because initial assumptions about stars yielded underestimated distances.
	www.hubblesite.org /newscenter/newsdesk/archive/releases/1994/49/astrofile (1151 words)

	The Hubble Constant
		Hubble's initial value for the expansion rate, now called the Hubble Constant, was approximately 500 km/s/Mpc or about 160 km/sec per million-light-years.
		The first major revision to Hubble's value was made in the 1950's due to the discovery of Population II stars by W. Baade.
		The uncertainties in the local determination of the Hubble Constant are still dominated by the uncertainty in the Cepheid P-L calibration, followed by uncertanties in the local flow field (non-Hubble expansion galaxy velocities).
	cfa-www.harvard.edu /~huchra/hubble (1275 words)

	"The universe according to Hubble"
		The Hubble Space Telescope, lookout for the planet since last year, has dazzled us with its amazing pictures, and brought us strange tales of galaxies, supernovas, and fl holes from the lonely reaches of space.
		Hubble's explanation also supported one of astronomy's favorite theories: that the universe began with a giant explosion called the Big Bang, which created matter and formed the galaxies.
		Since light travels at a constant speed, the size of the universe would be the distance light has covered since the universe began-which would also be the age of the universe.
	sln.fi.edu /inquirer/inquire2.html (1042 words)

	World Almanac for Kids
		Hubble estimated that the distance to the Andromeda galaxy was 900,000 light-years, a figure later corrected to 2.2 million light-years when astronomers discovered that the Cepheids were more distant than was first thought.
		This important relationship has become known as the law of the red shifts, or Hubble’s law; it states that the recession velocity of a galaxy is proportional to its distance.
		The ratio of the recession velocity of a galaxy to its distance (the Hubble constant) is now estimated to be between 50 and 100 km/sec per megaparsec (1 megaparsec equals 1 million parsecs).
	www.worldalmanacforkids.com /explore/space/cosmology.html (2391 words)

	Determining Hubble's Constant (Site not responding. Last check: 2007-11-05)
		Hubble's Constant is one of the most important numbers in cosmology today.
		Hubble's Constant is used to estimate the size and age of the universe.
		Hubble's Constant indicates the rate at which the universe is expanding.
	www.upei.ca /~physics/p221/pro00/hubble (87 words)

	The Hubble Constant as the Angular Velocity of Light in the Closed Universe
		In the mainstream cosmology the Hubble constant characterizes the rate of the Universe expansion, and the Hubble "constant" is changing there with the age of Universe.
		In this work the Hubble constant characterizes the rate of space expansion between the galaxies, which are absorbing the space.
		If we use the upper received value of Hubble constant 73.275, we'll have the radiation/gravity pressure ratio about 1.022, and the temperature of CMB will be smaller then observable in 1.0055 times.
	www.geocities.com /Area51/Nebula/3735/dates.html (906 words)

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